California police officers shot dead an unarmed man in his grandparents' back garden, after apparently mistaking his iPhone for a gun.

The Sacramento Police Department has released helicopter and bodycam footage that shows officers firing up to 20 shots at father-of-two Stephon Clark on March 18th.

Officers had responded to reports of a man breaking into at least three vehicles and a home in Sacramento.

Bodycam footage shows Mr Clark (22) being pursued by officers as he enters his grandparents' back garden in the dark of night.

An officer can be heard shouting "show me your arms, gun, gun, gun" before he starts firing rounds.

In the footage, both officers reassure each other that they have not been hit.

One adds later: "He's still down, he's not moving. We can't see the gun."

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No weapon was found at the scene after Mr Clark's death, and it is believed he was holding an iPhone 6.

"He was at the wrong place at the wrong time in his own backyard," Mr Clark's grandmother Sequita Thompson told the Sacramento Bee.

Police training expert Ed Obayashi told the newspaper: "It looks bad but (the officers) are still perceiving a threat, he's not obeying.

"The problem is he's got an object in his hand which unfortunately even during daylight could easily be considered a gun."

Sacramento Police spokesman Sargeant Vance Chandler said officers gave Mr Clark commands to show his hands after he fled.

"(Mr Clark) turned and advanced towards the officers while holding an object which was extended in front of him," he told the Sacramento Bee.

The death of the young father, who had two sons aged one and three, has been met with anger across California and US.

Protesters marched from Sacramento City Hall onto a nearby motorway on Thursday, disrupting rush hour traffic and holding signs with messages including "Sac PD: Stop killing us!".

Clinton Primm, a friend of Mr Clark, fears others are also at risk of being shot by police.

He said: "(Mr Clark) was a great dad. He loved both of them to death."

Sacramento Mayor Darrell Steinberg said he was horrified but would not second-guess the "split-second decisions" of the officers.

He praised the quick release of the helicopter and bodycam videos and said the police department had improved its policies since the fatal shooting of a mentally ill man in 2016.

A GoFundMe page has been set up to raise US$50,000 (€40,487) for Mr Clark's funeral expenses.